The yo-yo craze was started by an American soft drink company. You collected enough of their bottle caps, and you would be rewarded with a designer yo-yo.
This reminded me of the time 'Potato crackers' chips started to give surprise plastic toys free. We had to scratch the chips packet head to find out what surprise toy will come with this packet. Then the seller would give that to us. We stored those toys like they were our best assets.
